How interesting that the hygienist said that. It is one of their mantras that floss gets out the bacteria stuck between teeth; but yours went away on their own. This fits with the argument I shall propose, which is that chemistry is more important than cleaning methods in the mouth. And that a good diet improves the chemistry.

I have given up flossing. Feels an odd thing to say, since I took it up to help address a deterioration in my teeth that I thought was part of old age and thought I would be stuck with that awkward, unintuitive practice for the rest of my life.

Mouth Piece 2. Water

It took me some time to picture how teeth and gums are damaged--though it seems straightforward to me now. I believe it comes down to how acidic one’s saliva is. Acidity and alkalinity are far-reaching scientific phenomena, beyond my understanding in detail. But I have made an effort to grasp the basics, which I shall simplify (oversimplify) as follows. (Apologies, scientists: please look away.)

*

Life on earth is based on the structure of water. Human beings are largely made of water. Chemical reactions that involve water affect all parts of our bodies. Different chemical reactions take place according to how acidic or alkaline conditions are in relation to water. For example, a uric acid stone might form in an acidic body fluid and dissolve in a more alkaline body fluid. To measure the differences, scientists came up with a scale of acidity, called the pH scale, using water as the neutral reference point. Any substance with a pH of about 7 is considered neutral, because that is similar to water. Substances with a lower pH than water are more acid; and those with a higher pH than water are more alkaline.

Reactions take place in the body at varying levels of acidity or alkalinity. For example, the stomach produces highly acid juices to break down tough foods, but the stomach lining protects itself from acid damage by secreting carbonate, which is a buffering agent. In the same way, saliva is a buffering fluid that prevents acids from damaging the mouth and teeth.

In ideal circumstances, saliva would do this job perfectly. The body co-evolved its buffering systems with the foods it consumed. For this reason, natural foods should not damage the teeth. The body recognises the chemical structures of natural substances and responds accordingly. Within half an hour of chewing a naturally acidic food, such as an orange, the mouth returns to a neutral pH, before any damage has time to take place.

*

When I began thinking about this, it struck me that there are only two ways the mouth could be damaged by food. One would be if we eat non-stop, giving the saliva no time to clear the brief phases of acidity caused by meals (for example, if we constantly snack). The second would be if we eat processed food containing chemical structures the body has not been programmed through evolution to identify.

Having reached this point in my reasoning—that processed foods are, as usual, the bad boys of the piece--I was in store for a surprise. I read research which shows that some of the usual suspects, such as refined grains and carbohydrates, possess a relatively small capacity to damage our teeth and gums. Yes, they might induce a slight acidity that could cause long-term issues if overeaten--but saliva, it seems, can neutralise such foods fairly efficiently. No, it became rapidly clear to me that a single master-villain is at work in all this—refined sugar. Refined sugar--specifically sucrose--causes almost all tooth and gum damage single handed.

Mouth Piece 3. Fermentation

I am trying to talk about the science as minimally as possible, because I do not want to pretend I understand more of it than I do. Also, technical information is not my end point. All that matters to me is what helps me with my diet and health. However, I want to say something about fermentation, because it is the fermenting of sugar in the mouth that causes lasting, rather than passing, acidity, and which therefore results in damage.

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Earlier in this thread, I mused a lot about the lower bowel, because I believe the fermenting processes there to be as important to the life of our bodies as are the digestive processes of the upper bowel. Whereas in the upper bowel food is oxidised to release nutrients, in the lower bowel it is broken down by a non-oxidative method—anaerobic fermentation. This is the way primitive life forms, which evolved from bacteria, fed. Oxygen was not necessary.

In fermentation, millions of bacteria—which are living creatures—eat away at matter till its structure breaks down. As they do, they release acids as a by-product. Bacteria in the lower bowel produce short-chain fatty acids that can provide us with energy. The cells lining the intestine, for example, benefit considerably from these acids, which keep them healthy. But if we eat too many processed foods, our gut health suffers because the bacteria are starved of foods they evolved to consume.

*

Scientists do not claim to have studied all the many species of bacteria that live in the mouth. But they have discovered the methods that bad bacteria—such as streptococcus mutans—use to damage our teeth and gums. It is clear these bad bacteria thrive above all on refined sugar*, which is far easier for them to ferment than other foods, since all the resistant factors have been industrially removed from the natural sugar. The bacteria feed on the sugar that sticks to the teeth, and use it to form plaque and produce the acids that attack the teeth. Tooth damage benefits these bacteria, because they can breed bigger colonies in holes.

Bacteria cannot damage healthy gums; but a bad diet causes gum inflammation. Inflammation creates gum damage that provides more homes for bacterial populations. They particularly love the spaces between the gum and the tooth, which become swollen pockets of bacteria, protected from saliva and tooth cleaning.

This all sounds horrific. But it is avoidable at the drop of a hat. That is the conclusion I draw from the way my oral health was transformed the moment I stopped eating refined sugar. By no longer eating the refined sugar on which bacteria feed--and by leaving enough time between meals to allow saliva to do its work--I made it impossible for my mouth to stay acid long enough for damage to occur.

*

It took a while for the implications of my discovery to sink in; but once I began inspecting my teeth and gums in detail--noticing a new freedom from plaque, tartar, and inflammation--the way I view my teeth changed forever.

I had assumed, without thinking about it much, that it would be all downhill for my gnashers, now I am getting old. My teeth, I thought, will get worse and worse, till I am left with bits and pieces of broken stumps, crawling with rot, while I fork out vast sums of money to dentists just to stave off perpetual agony. I saw myself in my final days gaping toothless, with a maw like a Breughel beggar, sucking the juice out of milksops, flapping my gums on pap. Instead, I now know that teeth are not programmed to degenerate. And that if I stay clear of refined sugar and the products made with it, I can keep these teeth of mine—such as they remain--unto the very grave.


**

* When I talk of refined sugar, I mean sucrose, specifically. It happens that oral bacteria—for various chemical reasons--can very easily and quickly make sticky plaque out of sucrose. That is the reason it is by far the chief cause of tooth decay. Plaque forms a barrier against the neutralising wash of saliva, creating a much more acidic environment on the tooth surfaces than in the rest of the mouth. As far as I can see from the evidence, no other food has this instant plaque-forming capacity, including other forms of sugar.

Hi Plinge, very interesting posts, although I must admit that the holes etc. that you describe having, currently, in your teeth scare me a bit! Yikes!

My teeth have always been pretty great, but lots of plaque and the dental folks were always shocked that they were ok after they stripped them, though I did have an occasional cavity. I have never flossed regularly. Since switching to what I eat now, my checkups are always non-events and everyone at the dentist exclaims over how good my teeth are. Plus they never feel mossy like they used to. Also, I drink more coffee than EVER but it seems that the staining isn't as bad. I used to whiten my teeth or have them be totally yellow within months. Strange stuff.

Hi, Deci. They are not cavities, though. One is a bit that sheared off, and the other two are from fillings coming out. The exposed surfaces have filled over: I am coming on next to how that happens--seems miraculous, but it is what happens to healthy teeth, I have discovered, in a non-acidic environment.



The mossiness is from sucrose. I can chew dried fruit all day and get no mossiness from its sugars. My teeth could stain from tea and coffee, but I scrape them now and again. I do not think the stain is harmful to teeth--in fact tea contains substances that are good for the teeth.

Tooth whitening is a bit of a scam, I think. Teeth are not supposed to be white, but ivory.

*

I am so excited about all this. It is said that oral health is a good indicator of bodily health, and I think nothing tells us that our healthy diets are doing us good better than a trouble-free gobtasia (to make up a word).

I was picturing a big hole from the one still there! I am, indeed, curious to hear about teeth healing over. It does seem miraculous. I would like that to be the case. I would also like our chops to be less breakable due to this WOE. And here I thought drinking all that milk would help.

Gobtasia is a most excellent word, I am stealing it. I am far enough away that I can take full credit here.

Drinking milk and eating dairy most definitely helps!

I think enamel does get more brittle with age, and some of it wears away. But this need not be a problem. There is a tribe in Africa that used to file their teeth into points, removing large areas of enamel; and until western foods came to them, they did not suffer tooth decay, and they kept their teeth all their lives.

I am going to muse about this later, but I am inclined to blame the breaking of my teeth on fillings. It turns out that though enamel is brittle, it rests on more cushiony substances that can adjust to all the forces exerted on the teeth. When dentists drill into that malleable layer to insert completely unmalleable substances, such as the metal my teeth are full of, they reduce the flexibility of the tooth. In the end, I think, the pressure can lead to bits of enamel chipping off when the fillings come out--especially if you are older and the enamel has thinned. That is just a theory; but the more I think about it, the less I trust fillings. I would have all mine out, if I could afford it, and then see how I got on without any.

Mouth piece 4. How to grow back your teeth.

I jest. Obviously, if you lose a tooth, or a piece of tooth, you cannot grow it back like a crab claw. But here it is. If you have cavities, you can make them heal them over with new enamel. And if you lose a piece of tooth, you can heal the damaged area over with new dentin.

The first inkling I had of this was when, as I said earlier, my broken teeth acquired new, smooth surfaces with the passing of time. I would not have discovered the phenomenon had I kept to my dental check-ups. Till then, when my teeth were damaged, the dentist filled them in with whatever substance was in vogue at the time. I could only guess what would happen if he did not.

*

After my oral health blossomed during my low-carb diet, I read up on dental science. A most unexpected finding was that teeth can mend themselves--but what surprised me at first now seems common sense. After all, teeth are a form of bone, and bone can mend itself by integrating minerals and proteins from the diet into its fabric. Teeth do that too, though they are made differently from normal bone.

Teeth have four main layers. The inside part, which links with the blood supply, contains flesh and nerves and is called the pulp. The pulp is protected by a semi-hard layer of cementum, which, like bone and cartilage, contains lots of collagen. Over that grows a layer of dentin, a hard but not brittle substance resembling bone. The dentin is covered by a brittle layer of enamel, which is normally as hard as rock.

Enamel can be eaten away (as I said in my last post) by acids, which cause cavities and rot. It can repair the damage with the aid of minerals such as calcium, phosphorus, and fluoride, so long as those are sufficiently available in the saliva.

Areas of enamel can also be lost through wear and breakages. When that happens, the tooth heals from within. Dentin grows over the broken or exposed areas and forms a serviceable replacement for enamel, though it does not look so white. (The reason teeth get more ivory with age is that dentin starts to show through worn enamel.) Dentin is not as hard as enamel, but it is hard enough to provide a biting surface, and, crucially, to seal up the inner tooth and keep acid and bacteria out. For this to happen, however, the owner of the teeth needs good oral health, with non-acidic saliva which encourages growth of dentin and discourages bacterial damage.

It is as simple as that.

Mouth Piece 5. How toothpaste works.

I would not be surprised if a reader of my last post raised an eyebrow. That simple? Really?

In theory, yes, I believe it is. In practice, though, most people eat processed food; and to preserve their teeth and gums in the way I described, they must eat clean. Suddenly, not so simple at all.

*

I have become sceptical about many practices of the dental profession. The more treatment people need, the more money dentists make—so can they be trusted? Well, I do not believe dentistry is a conspiracy. Faced with patients who coat their teeth with sugar, which they fail to clean off quickly enough, dentists provide a remedial service, mending the damage that results. They may remind us to eat less sugar or clean our teeth better; but ministering to our overall health is beyond their remit. The hourly state of our teeth is our responsibility, not theirs.

Though we are not routinely told that enamel can reform and dentin regrow, orthodox tooth care provides the clues. We learn, for example, that calcium is good for the teeth. I assumed calcium helped them grow well. But if that is all calcium does for teeth, why are we still advised to consume calcium once our teeth are grown? Logically, if calcium is good for mature teeth, then teeth must be subject to repair, like bone. Their structure must be dynamic, in common with other bodily tissue.

I also assumed calcium benefits teeth via the bloodstream. We consume, say, milk, and its calcium enters the blood, reaching our teeth from within. In fact, I now understand that dairy products, for example, also benefit the teeth topically. In other words, they mix with saliva, and when that saliva bathes our teeth, the minerals (and proteins) in dairy foods adhere to the teeth and are laid down directly in the enamel and dentin, through chemical reactions. This happens with all mineral-rich foods--dairy is just the best known The process is one of gain and loss: minerals and proteins are constantly lost from the teeth and replaced, as they are in other body tissue. If an acid solution can remove minerals from the teeth, then an alkaline solution can reverse the process and add them. Demineralisation and remineralisation occur all the time on tooth enamel, according to the pH of the saliva.

This became even clearer to me when I considered toothpaste. We do not eat toothpaste, we brush it onto our teeth. Why? I had thought of toothpaste as a glorified cleaning product, along the lines of kitchen cleaner. But if that were the case, it should contain only soap and abrasive. In fact, toothpaste contains minerals such as calcium, phosphate, and fluoride. What reason could there be for including such minerals except to lay them down into the fabric of our teeth? Toothpastes also contain buffering agents to make the mouth less acidic. They help provide the neutral conditions for the reactions to take place that incorporate minerals into the teeth.

So although the dental industry makes its money from remedial work, the intention behind its products is not just cleanliness but also the daily protection and mending of teeth on a sound scientific basis.

Now that you mention all of this, I did chip off a hunk of my front tooth years ago, and it is not noticeable now. I don't think I've filed the whole shebang down over the years gnawing on stuff... interesting.

It is a form of wound healing, I think. The same way skin grows back. The body will not allow bacteria into the bloodstream if it can help it. Once enamel chips off, the tooth would be vulnerable then, so it seals itself up.

Mouth Piece 6. May Mellanby

The first time I read that teeth could heal themselves I did not believe it. I thought it was more raving by an internet fantasist. Then I came across a series of British health reports from the 1930s and 40s in which the subject was taken seriously. I soon discovered that many early dental scientists and dentists believed in it.

Once evidence mounted that milk helped not only in the formation of children’s teeth but in healing caries in their teeth, free milk was introduced for all British schoolchildren in the 1944 Education Act. When the British government withdrew free milk from secondary schools in 1968 and then from children over seven in 1971, I think that betrayed a reversal to the assumption that milk helps only in the formation of teeth. The knowledge that milk could help nurture the dental health of children until adulthood seems by then to have gone underground.


*

The British medical scientist May Mellanby performed a series of experiments on dogs in which she showed that secondary dentin forms to protect teeth against rot, damage, and wear. In a 1936 report to the British government, she wrote:

“The extensive translucent zone in the primary dentine and the large amount of secondary dentine often found in arrested caries are evidences of the potent reaction of the tooth…If the secondary dentine is well formed, the damage produced by the caries is more likely to be slow or arrested than when it is poorly formed…The few results obtained so far in regard to the relation of diet to the structure of secondary dentine in animals indicate that this relationship is similar to that already shown to exist between diet and the structure of enamel and primary dentine. If this should ultimately prove to be the case, it will be evident that not only is the structure of teeth controlled by the diet during their development but also that their subsequent resistance to caries and other harmful influences is dependant on the food and more especially on certain substances supplied to the body …” (May Mellanby, “The influence of diet on caries in children's teeth”, Medical Research Council, Special Reports Series, 211, London: H.M.S.O., 1936.)

Other dental experts, including the Canadian Weston Price, in his 1930 book Nutrition and Physical Degeneration, had come to similar conclusions. The “certain substances” mentioned by Mellanby, including nutrients such as the fat-soluble vitamins A and D, were also advocated by Price.

*

By the time I was born in 1954, informed mothers (such as mine) routinely gave cod liver oil, which contains vitamins A and D, to their children. My sister and I were laughing about this only the other day—I am talking about huge spoonfuls at a time, not the sissy little "children's" capsules you get today. That and the free school milk might be why I do not remember any children at my school with crooked teeth. We might have been poor, but we were born with tablespoons in our mouths.

Mouth Piece 7. Why is refined sugar worse than other sugars?

I find this difficult to answer.

On the face of it, one sugar is much the same as another. We mainly eat refined sugar in the form of sucrose, which is a disaccharide--in other words two sugar molecules (one of glucose and one of fructose) bonded together. Natural sugar does not contain much sucrose; instead it contains lots of glucose and fructose as single sugars. In theory, there should not be much difference between the effect of sucrose, which is made of glucose and fructose, and the effect of single glucose or fructose sugars on the teeth.

In practice, however, there is a big difference. Refined sugar sticks much more easily to the teeth, and the mouth’s bacteria are able to make it stay there in plaque, whereas natural sugars are much more easily cleared from the mouth, because they are attached tightly to the food they are part of. Some people define this difference as between extrinsic sugar and intrinsic sugar—ie., between “free” sugar and sugar eaten as part of plant material.

Perhaps the disaccharide formation of sucrose does make a chemical difference; but I think the most likely difference is that sucrose has been isolated from the fibres in which it was embedded before being refined, leaving it unprotected from oral bacteria. Other refined free sugars—such as high fructose corn syrup—are probably just as vulnerable. But unrefined sugars, such as those in fruit, whole starches, and milk do not seem to readily cause tooth or gum problems.

*

For example, compared to sucrose, the sugar in dried fruit is closely bound up in plant matter. To extract sugar from raisins or dates, you have to chew hard, and when you swallow, much of their sugar goes down the hatch too, still locked in the plant cells. Even the part of dried fruit sugar that mixes in the saliva will be accompanied by other compounds from the dried fruit, which may be protective against tooth damage. The reason they are protective is that in nature plants want to stop their sugars from breaking down, so they contain multiple substances for the purpose.

Plausible though that explanation seems, it is difficult to prove, because science is still in the earliest stages of studying the synergy of food components. There remain vast numbers of unknown compounds in a food such as dates, so much guesswork is involved in explaining why sucrose is particularly damaging.

Nonetheless, scientists discover new synergies all the time, and they have found plenty in dried fruit. (The reason I choose dried fruit as an example is that I eat a lot of it, so I am curious to know why such a sticky, sugary food leaves my mouth plaque free.) It seems, for instance, that raisins contain many substances that actively prevent plaque formation and protect tooth enamel.

Here is a quote from a report that mentions some of these substances—most of which I have never heard of. The gist is that raisins are harmless to the teeth thanks to various protective nutrients in them--such as would be removed from sugar in a refinery. (This is from University of Illinois College of Dentistry but funded by the California Raisin Board, so some caution is due.)

“Raisins contain polyphenols, flavonoids, and high levels of iron that may benefit human health. However, their oral health benefits are less well understood. We hypothesized that raisins contain antimicrobial phytochemicals capable of suppressing oral pathogens associated with caries or periodontal diseases and thus benefit oral health. Through antimicrobial assay-guided fractionation and purification, compounds identified with growth inhibition against oral pathogens were oleanolic acid, oleanolic aldehyde, linoleic acid, linolenic acid, betulin, betulinic acid, 5-(hydroxymethyl)-2-furfural, rutin, beta-sitosterol, and beta-sitosterol glucoside. Oleanolic acid suppressed in vitro adherence of cariogenic Streptococcus mutans biofilm. When the effect of raisins and raisin-containing bran cereal on in vivo plaque acidogenicity was examined in 7- to 11-y-old children, it was found that raisins did not reduce the plaque pH decline below pH 6 over the 30-min test period." (C. D. Wu, “Grape products and oral health”, J Nutr., 2009.)

*

It is possible that the bacteria streptococcus mutans has a specific chemical affinity with sucrose, explaining why the latter is so rapidly fermented into acid.

“While sugars appear to differ little in acidogenic potential, sucrose has been given special importance, as the sole substrate for synthesis of extracellular glucans. Water-insoluble glucans might enhance accumulation of mutans streptococci on smooth tooth surfaces and appear to enhance virulence by increasing plaque porosity, resulting in greater acid production immediately adjacent to the tooth surface.” (D.T.Zero, “Sugars – The Arch Criminal?”, Caries Research, 2004.)

“A high sucrose intake is associated with increased plaque volume due to the production of extracellular glucans, and there is a strong association between plaque volume and gingivitis. Human intervention studies have shown higher plaque volumes and increased gingivitis with high sucrose diets compared with low sucrose diets.” (Moynihan & Peterson, “Diet, nutrition and the prevention of dental diseases”, WHO Report, Public Health Nutrition, 2004.)

Mouth Piece 8. Reasons to be cheerful

I used to think all processed food was as likely to cause tooth decay as refined sugar. Having looked into it, I find that is not the case--though the more refined sugar a processed food contains, the worse for the teeth the product will be. That is not to say refined grains or starch cannot ferment on the teeth; it is just that they ferment so slowly that they are usually cleared by the toothbrush before they can get going. This difference has been demonstrated in various laboratory experiments. For example, in the case of starch:

“Starch is not transported across the cell membrane of plaque micro-organisms and so cannot be metabolised by oral bacteria to produce acid. However, salivary amylase may hydrolyse starch to produce glucose, maltose, and maltotriose, all of which may be taken up and metabolised by bacterial cells.” (Paula Moynihan, in “The Prevention of Oral Disease”, ed. Murray, Nunn, & Steele, Oxford University Press, 2003.)

In other words, it takes time for starch to start damaging teeth--in contrast to sucrose, which can set to work almost immediately.

*

Another food I always suspected of damaging teeth is fruit. According to Moynihan (see above), only one human study has ever reported tooth damage from fruit. It was a study of apple farm workers and grape farm workers, who liberally ate apples and grapes all day without cleaning their teeth. In this case, though the damage was slow, it had time to build up. (Even here, the apple workers were free of gum disease, thanks to vitamins in apples that support collagen.)

Other than in this extreme example, fruit consumption has been found to correlate with good oral health. It seems that though fruit is acidic, chewing it stimulates enough saliva to prevent a steep or lasting drop in pH. Also, as with dried fruit, fresh fruit contains not just sugar but many factors that protect oral health. Fruit juice, on the other hand, is more dubious, because processing removes from it many protective factors and sharply increases the proportion of free sugars. “It is preferable to consume whole fresh fruit,” says Moynihan, “because their mastication provides a good stimulus to salivary flow. Also, fruit juice contains extrinsic sugars, since liquidation releases the fruit sugars from the cellular structure of the fruit.”

*

Lactose, a sugar found in milk, also seems harmless to teeth. This is hardly surprising, since milk is designed to nourish the tissues of baby animals, including their teeth, not damage them. Its sweetness encourages babies to feed. It always struck me as odd that nature would instil a lust for sweet things in the young which often lasts their whole lives and may sow the ruin of their teeth and health. But if natural sugars are indeed harmless--when consumed with their protective fellow nutrients--then it was a good survival strategy for humans to evolve a taste for sweet, high-energy foods. Unfortunately, this love of sweetness has led too many of us modern humans to flood our bodies with refined sugar, an alien foodstuff against which we have few genetic defences. (See Touger-Decker & Van Loveren, “Sugars and Dental Caries”, Am J Clin Nutr, 2003.)

*

One piece of good news is that refined sugar is less damaging, or is neutralised altogether, when eaten with real foods. For example, studies have demonstrated that chocolate and strawberry flavoured milks—which contain added refined sugar—are relatively harmless to the teeth. This is because the minerals and proteins in the milk that render lactose harmless also render added sugar harmless. (I never used to give my children flavoured milks, because I thought they were as bad as other sugary drinks. If only I had been better informed, as two of my girls would not drink straight milk, yet they loved a milk shake on holiday.)

“Dental health educators need to know if [flavoured milk] and other sugar and fruit juice sweetened milk products, such as fruit yoghurts, are acceptable as snack items. Available evidence suggests that their cariogenicity is negligible to low and consumed in moderation they are a preferable alternative to similarly sweetened soft drinks.” (R. S. Levine, “Milk, flavoured milk products and caries”, Br Dent J., 2001.)

Similarly, laboratory experiments by Bibby et al (J. Dent. Res., 1980) showed that adding dried whole milk or skimmed milk to cakes made of sucrose and starch significantly reduced tooth rot. Interestingly, whole milk performed better than skimmed, which confirms the view, going back to Weston Price, that fats have a role to play in dental health.

Although I try not to eat refined sugar at all, such reports incline me to think a little sugar here and there—say, sprinkled on rhubarb—might do little harm. Sucrose is virtually unavoidable when eating or drinking away from the nutritional stronghold of one’s kitchen. Oral harm seems likely to occur only when our diet consists mainly of processed food, which lacks the nutrients to inhibit the work of refined sugar. And only then if one fails to clean one’s teeth in timely fashion. Eating a little refined sugar along with good food, as one does at restaurants, is unlikely to be a problem. In future, I shall be less neurotic about that.

"Waiter, one banana split, and pronto!"

Mouth Piece 9. Time on the teeth

I am now so convinced the mouth is a self-righting environment that I believe it might cope even with a highly processed diet, so long as it is kept clean and allowed time to recover between eating bouts. A prolonged acid mouth pH makes tooth rot inevitable; but a sustained neutral mouth pH makes tooth rot physically impossible.

No one on this site needs lessons in toothcare; but allow me to scratch at the subject for a while, to help me edge towards a theory that less toothcare (and less money spent on dental services!) might be not only possible but preferable—so long as we eat healthily. As my latest heroine May Mellanby wrote: “There is indeed evidence that hygiene practices are of little importance in preventing or arresting tooth decay, although the esthetic value of the toothbrush cannot be denied” (“Diet and the teeth: an experimental study”, Medical Research Council, 1929). She came to that conclusion both from her experiments and from studying the geographical distribution of tooth decay, which revealed populations with low tooth decay that used neither toothbrush nor toothpaste but which did eat foods rich in calcium, phosphorous, and fat-soluble vitamins.

*

The obvious way to remove plaque from the teeth is to brush regularly. I am not sure even that dental products are necessary. True, toothpaste contains agents to help enamel remineralise, but saliva can achieve that on its own provided the diet contains calcium and phosphorous, which are in most whole foods.

Alas, when I was growing up at home and eating processed food, I cleaned my teeth only in the morning. At boarding school, where my dental health improved, we were made to clean them twice a day and inspected in the evening by a ferocious nurse with a torch (who also scrutinised our knees, heels, and, I think, moral fibre.) Not till I reached my fifties did I start brushing my teeth after all meals, in a desperate rearguard action against rampant deterioration in the gnashers department. I also took up flossing, gargling with the stiffest mouthwash this side of sulphuric acid, and using an electric toothbrush so big it felt like sticking a miniature carwash in my mouth. In truth, though I talked with shame of the state of my teeth, by the time I started my low-carb diet—which quickly changed everything—no one could have accused me of poor dental hygiene. I rolled up my sleeves every night and went at my teeth hammer and tongs, with the frenzied paranoia of a medieval housewife scrubbing every nook and cranny of her dwelling against plague and damnation.

Now that my dental health is reborn, I am back to cleaning my teeth just twice a day, and lightly, with only a soft toothbrush. I deploy a dental pick when something is stuck in my teeth. I may briefly chew dental gum after meals. And that is it. No flosses, dental tape, whiteners, breath fresheners, tongue scrapers, mouthwashes—no toothbrushes hard enough to take rust off an iron gate.

I suspect I could with little harm give up daily toothcare altogether, so sure am I now that the mouth can clean and repair itself. Primitive man lacked our dental practices, yet, according to archaeology, his teeth, like those of wild animals, stayed rot free, though they did get very worn down. I am sure, however, that early people used toothpicks, etc. to dislodge fragments of food, such as half acorns, scorpion legs, and the like. When I was in the boy scouts, we were taught how to clean our teeth with a frayed twig in case of emergencies, for instance an enemy siege. It would be obtuse for me now to forgo my toothbrush just to prove a point. I continue with my brush and toothpick because, as May Mellanby acknowledged, aesthetics come into the picture. No one wants to gad about with a shred of tomato skin stuck out of their front railings like a red flag of neglect.

Even in a healthy mouth, kept at an ideal pH, the occasional stab of tooth or gum pain occurs. For me, it is when a particle of food gets trapped between my rear teeth and gums. In such cases, the area beneath the object becomes sealed off from the cleansing wash of saliva, so the pH in that micro zone becomes acidic, enabling bacteria to grow and rot to set in. For this reason alone, brushing is worthwhile, plus the precision use of a pick. Nonetheless, when I brush my teeth at bedtime, I am surprised--particularly as a nut eater--how few visible particles of food appear in my toothpaste spit. In the absence of plaque, little food seems to adhere, even to my damaged back teeth, which resemble the walls of Constantinople just after Suleiman the Magnificent's bombardment.

*

Though I believe the mouth’s self-cleaning mechanisms could cope even with sucrose, that would depend on sufficient intervals between eating episodes, to allow the saliva to neutralise again and whack the plaque. When, however, people constantly snack on processed food, their saliva stays acidic all day: under such circumstances, their teeth will be damaged. Plaque builds up hour by hour, sucking ever more sugar into itself, and where it lies against the teeth becomes a hive of bacteria and acid production.

So I think the danger lies not in how much sugar we eat but in the time sugar spends on the teeth (there are studies showing this). If we eat sugar, we should clean the teeth after doing so—including during the day—and make sure not to undo the benefit by popping jelly babies, chocolate drops, or whatever, every five minutes. No need to whip out an electric toothbrush in the middle of the office. A stick of dental gum—any sugar-free gum—will do a quick job of buffering the saliva, and the day will be saved. If we do not usually eat refined sugar—as I do not—such precautions are rarely needed. In fact, I daresay we nutritional paragons might abandon the larger part of toothcare yet retain our dental health. Humans are designed, like all animals, to let nature take care of their teeth.